Evaluation of resistance mechanisms and epidemiology of Acinetobacter isolates from intensive care units in a Turkish university hospital

Abstract number: R2305

Altun B., Hascelik G., Akova M.

Objectives: Multiresistant Acinetobacter spp. (MR-A) are responsible for the increasing number of nosocomial infections. Local epidemiolgy has outmost importance for determining therapeutic options in patients infected with MR-A.

Methods: We examined one-hundred-fifty Acinetobacter baumannii strains isolated from blood cultures between 1997 and 2007 at the Hacettepe University Medical School. All of the strains were isolated from nosocomial infections. In vitro activity of netilmicin, amikacin, ciprofloxacin, imipenem, piperacillin, cefoperazone/sulbactam, tetracycline and colistine, were evaluated by the minimal inhibitor concentration (MIC) technique using broth microdilution method according to CLSI criteria. Presence of PER-1 and other b-lactamase profiles (IMP-1, VIM-1, SPM and OXA-58) of the strains were determined using PCR. DNA fingerprinting by PFGE was used for epidemiological analysis of the strains.

Results: Resistance rates are given in the Table. Sixty (40%) of 150 isolates were found positive for PER-1 gene. No isolates with IMP-1, VIM-1 and SPM genes were determined. OXA-58 was detected in 75 (50.0%) of 150 isolates. Eight distinct patterns were detected with genomic fingerprinting by macrorestriction analysis with PFGE.

Table. In vitro susceptibility of Acinetobacter isolates

Conclusions: In a multiresistant population of Acinetobacter isolates, PER-1 and OXA-58 were frequently detected. Along with the other possible mechanisms, these two ESBL-type of enzymes seem to contribute to multiresistance pattern of our Acinetobacter isolates.